#include<iostream>
#include<cstdlib>
using namespace std;
int a[5][5];

int f()
{
	int i,j;
	for(i=0;i<m;i++){
		for(j=0;j<n;j++){
			if(i==0 || j==0)
				a[i][j]=1;
			else{
				a[i][j] = a[i-1][j]+a[i][j-1];
			}
		}
	}
	return a[i-1][j-1];
}

int main()
{
	
	cout<<f()<<endl;
	return 0;
}
